Method of applying connectors



Oct. 26, 1954 F. L. PIERCE 2,692,422

METHOD OF APPLYING CONNECTORS Filed March 10, 1948 v3 24 w gqrj L5 m 20 (Iifomegs Patented Oct. 26, 1954 METHOD OF APPLYING CONNECTORS Frank L. Pierce, Camp Hill, Pa., assignor to Aircraft-Marine Products Inc., Harrisburg, Pa.

Application March 10, 1948, Serial No. 14,109

1 Claim. l

This invention relates to electrical connections, and to methods and apparatus for making the same.

Over a long period of time there has been interest and more or less intensive commercial development of connections between wires, cables, bus bars, tubes and like electrical conductors with terminal connectors, splice connectors and direct connection to ferrule forming parts wherein the metal of a ferrule forming strip or tubular element is made to embrace the wire or other conductor, etc., and is then swaged or pressureformed thereon so; as to make a secure and permanent connection. For many years connections of this type had been considered suitable only for special application and never gone into extensive use to replace soldered connections or mechanically clamped connections. Improvements of recent years, however, have, altered this situation to such an extent that connections of this kind have now all but displaced soldered connections in all high quality electrical manufacturing and have largely replaced mechanically clamped connections. The present invention relates to a further improvement in this type of pressure-formed connection whereby the quality and permanence of the connection is still further substantiall improved.

According to the present invention the form ing of the ferrule and particularly its compression by which it is deformed and in turn deforms the wire, etc., takes place progressively from an end remote from that into which the wire, etc. extends. In this manner the metal is extruded longitudinally beyond the ferrule and wire, etc. from under each point thus producing a progressive movement longitudinally toward said end. This facilitates the forming of the inner surface of the ferrule to the exterior surfaces of the wire, etc., and by reason of the longitudinal extension, breaks any oxide film which may have formed on the surface of the metal and by reason of the longitudinal flow scours the surfaces, much as glacial flow of ice is known to have scoured the surface of the earth, all with the consequence that when the pressure forming (sometimes referred to in this art as crimping) of the connection is completed there is a connection which is substantially perfect electrically, i. e. free from substantial contact drop, which is strong and secure mechanically and which is so effectively sealed that it is highly resistant to corrosion.

This is effected most advantageously according to the present invention not by any mere compression at progressive points along the surface but by a compression which occurs first at the remote point and progressively along the length of the ferrule while at the same time increasing progressively in extent at each point along the ferrule.

A further improvement according to the present invention resides in terminating the compressive deforming of the metal at a point near but spaced from said end of the terminal into which the wire etc. extends. By this expedient the metal, which is extruded longitudinally more freely near the inside of the ferrule than at the face of the compressing die, pushes out the exposed edge beyond the end of the die thus forming a flare and a smoothly rounded lip which minimizes any tendency to breakage of the wire, etc., by sharply localized fatigue.

Instead of using dies which converge slightly from end to end ordinary parallel die sets can be used with similar effect if more metal is present in one end than the other, e. g. by progressively increasing thickness or by sloping edges in the ferrule-forming blank.

In the accompanying drawings I have shown several preferred embodiments of the invention and will describe these below and various modifications thereof. It is to be understood, however, that these are not exhaustive nor limiting of the invention but are selected and presented with a view to instructing others in the principles of the invention and manner of using the same and illustrating and explaining the invention so that others skilled in the art may be enabled to adapt and modify it and apply it in numerous forms each in accordance with the requirements of a particular use.

In these drawings:

Figure 1 is a view in vertical transverse section through a completed connection in the crimping dies;

Figure 2 is a central longitudinal section of the same;

Figures 3 and 4 are views similar to those of Figures 1 and 2 but showing a different type of crimped connection;

Figure 5 is a perspective view of a die set designed for use in the present invention;

Figure 6 is a fragmentary view in vertical axial section taken through the die set of Figure 5, with a cl'imped connection completed therein.

Referring first to Figures 1 and 5, I have shown a connector in the dies at the end of the operation of pressure-forming on a stranded wire. This type of connection and the method of application as well as the dies shown are more particularly described and claimed in a copending application of James C. Macy, Serial No. 717,842, filed December 23, 1946, now Patent No. 2,600,012. In accordance with the present invention, however, the die faces, instead of being parallel to a common axis, are arranged so that they converge slightly in a direction opposite to that in which the wire extends from the connector. In the case illustrated, the end of the supporting die if) is substantially perpendicular to the axis of its movement, but the curling die I2 is provided with semi-cylindrical faces i3 whose axes are at a small angle to the face of the supportin die it. e

The face of the supporting die it may be subdrical or semi-elliptical or V-shaped in cross-' section, i. e. dihedral. When a U-shaped-or V- shaped blank is inserted into this die set and a wire inserted between the sides of the U or V and the dies then closed together, the sides of the blank are first driven up into cylindrical faces of the curling die and then are bent and with further closing the sides are driven over these surfaces being curled and redirected back toward the central area. of the ferrule being formed and into engagement with the wire therein, This action occurs most strongly at the end of the ferrule opposite that from which the wire extends, that is to say, the end of the ferrule at which the space between the supporting die and the curling die is less. As the closing together of these dies is continued, the edges of the ferrule portion are driven into the wire eventually meeting with such resistance that the metal of the wire and of the edge portions of the ferrule and at the sides of the ferrule are all deformed by the compression due to the closing of the die. This compression first drives the metal into the interstices between the stranded wire and between the wires and the ferrule. When these interstices are filled, and to some-extent even before that, the metal is extruded-longitudinally to a point where the compression is less due to the sloping arrangement of the dies. As the compression proceeds this extrusion of metal occurs progressively along the length of the ferrule and the enclosed wire for a substantial distance, thus assuring a scouring of the contact surfaces, and an improved contact from an electrical point of view and from the point of view of resistance against corrosion and a more secure mechanical connection from the point of view of high pull out strength equalling or exceeding the tensile strength of the wire itself.

If the relative slope between the dies is such that the extrusion of the metal continues substantially to the outer end, the metal in the interior of the ferrule is extruded beyond that which is in contact with the die face and therefore restrained to some extent against extrusion with the consequence that a bead I5 is pushed out and flared as indicated in the drawing and this head provides a smooth bearing for the extruded Wire distributing flexing strains and avoiding sharply localized fatigue.

Although I have described the ferrule above as being made from a U- or V-shaped blank, it may also be initially closed to substantially cylindrical form with abutting edges and the edges turned in by the central ridge is on the Cllllillg die.

In Figures 3 and 4 I have shown another type of connection wherein, instead of the parallel cylindrical surfaces of short radius, the closing die is formed with a longer radius curvature. In this case no central ridge is provided. As a consequence the sides of a U-shaped blank are closed by being pushed along the faces of the die until they are brought together and therefore further closing of the die deforms the metal at the sides of the ferrule and by the pressure transmitted through them may deform also the metal of the wire etc. within. By providing a slight longitudinal convergence between the faces of the supporting die 10a and the faces 13:]. of the curling die [2a the same longitudinal extrusion and improved results are obtained as de scribed above.

In the Figures 5 and 6 I have shown another type of connection which is broadly described and claimed in a copending application of James C. Macy, Serial No. 580,841, filed March 3, 1945, now Patent No. 2,639,754. In this case overlapping plates [8 and 20 are provided with die faces l3b and Mb and apertures 2| leading to the die faces.

Between adjacent die plates are spacer plates 22 and 23 each of which is provided with a die projection 24 extending into the apertures 21 so as to bring its die face in line with that of the adjacent plates 20 or 2|. The die surfaces in this case are arranged on a converging slope. as illustrated and when these assemblies of plates are pressedv together with a ferrule-forming member and a wire therein the ferrule is closed onto the wire and the metal of the ferrule and wire progressively deformed and extruded longitudinally as above described.

In the same manner as illustrated above for the three types of dies shown, this invention. is applicable to other dies which confine the connection while it is being compressed and the method as described above is broadly applicable, in the field of pressure-formed connections.

What is claimed is:

The method of making an electrical connection which comprises forming a connector of malleable metal with a ferrule-forming portion, assembling a conductor with a bare portion thereof extending into contact with said ferrule-forming portion, forming said ferrule portion to surround and embrace the conductor, and, While confining the ferrule against radial extrusion, deforming the metal of said ferrule and conductor by transverse pressure beginning at a point remote from an end of the ferrule into which said conductor extends and progressing longitudinally to a point adjacent said end, while. the pressure is increasing progressively at each point therebetween, whereby the metal is caused to flow longitudinally toward said end with lengthening of the ferrule, a scouring of the contacting surfaces by said flow and a conforming of the surfaces of the ferrule and wire in effect substantially sealing them against corrosion, the transverse pressure for deforming said conductor being terminated at a point substantially spaced from said end of said ferrule and a narrow band at said end being unconfined, whereby the longitudinal extrusion of metal along the interior of the ferrule pushes said unconfined end portion radially outward with production of a smoothly flared lip.

References Cited in the file of this patent UNITED STATES PATENTS Number (Other references on following page) Number UNITED STATES PATENTS Name Date Gieshoidt Jan. 21, 1902 Newman Feb. 11, 1908 Brown Feb. 15, 1921 Thompson Mar. 19, 1929 Fortner July 28, 1931 Hayford. June 14, 1932 Mansbendel Jan. 23, 1934 Anderson May 22, 1934 10 Brenizer Apr. 28, 1936 Number 6 Name Date Oppenheim Aug. 11, 1936 Davis Mar. 1, 1938 Schwerin Oct. 17, 1939 Hayden Nov. 18, 1941 Hackbarth Nov. 24, 1942 Carlson Sept. 26, 1944 Carlson Aug. 14, 1945 Baule Nov. 12, 1946 Aldeen Sept. 9, 1947 Brickman Feb. 8, 1949 

